Two Answers to Deep Time
If you search for the oldest archaeological site in North Dakota, one number keeps showing up: 11,600 BC.
Sounds settled, until you ask the obvious question: where does that number come from, and what is it actually tied to?
This isn't about who was first in the Americas. We are staying inside North Dakota and answering a tighter question regarding how strong the documentation is behind the state's oldest claim.
The evidence-first takeaways:
- Beach Cache (32GVX48): A deliberate stash of Clovis-era stone tools placed for later retrieval.
- Reported Date: 11,626 ± 68 radiocarbon years (roughly 11,600 BC).
- The Asterisk: The date is widely cited, but the lab code isn't in public-access summaries.
- Beacon Island (32MN234): The securely dated Agate Basin alternative with full lab-code transparency.
Commonly cited is not the same as fully documented.
The Claim: The Beach Cache
The name that keeps coming up is the Beach Cache, located in southwestern North Dakota.
This isn't a village. It isn't a kill site. It is a deliberate stash of stone tools placed for later.
Caching implies planning. It means a group mapped this location as useful enough to mark a return to, leaving behind a toolkit consistent with the Clovis world.
It gets the "oldest" label because it is frequently paired with a reported charcoal radiocarbon age of 11,626 RCYBP.
The Lab Code Gap
Can we trace that charcoal date like a receipt?
In the public-access sources, that Beach Cache number is repeated, but the radiocarbon lab identifier isn't shown alongside it.
That lab ID matters because it ties a date to a specific sample from a specific lab with a documented context in the ground. A missing lab ID doesn't mean the date is wrong. But it means you cannot independently audit the sample line-by-line.
Beach Cache holds the headline answer, but the asterisk must remain visible.
The Verifiable Anchor
What happens if we compare it to a North Dakota site that does publish the lab-coded trail?
That is where the Beacon Island site in the Lake Sakakawea reservoir area becomes useful. It includes an Agate Basin bison kill and butchery component supported by multiple radiocarbon assays.
Crucially, it comes with explicit lab codes (like CAMS-90966 and ETH-26780).
Converted into BC terms, that cluster lands roughly around 10,400 to 10,100 BC. Beacon isn't necessarily the oldest claim that gets repeated, but it is the one you can independently verify.
What This Changes
Both statements can be true because they are answering two different versions of "oldest."
If you mean the site most commonly labeled as North Dakota's oldest dated archaeological site, the answer is the Beach Cache.
If you mean the oldest Ice Age occupation in North Dakota with publicly listed, lab-coded dates, Beacon Island is the cleaner anchor.
Further Reading
- State Historical Society of North Dakota — Paleoindian Study Units
- Chronicles of the First North Dakotans: Earliest Archaeological Sites
- University of New Mexico Press — Clovis Caches